Investigation of radiation-induced mixed interstitial configurations in a dilute nickel 1 at.% silicon alloy

Abstract

X-ray energy spectra induced by 1 MeV protons and the energy spectra of the backscattered protons have been examined in the <100> and <110> directions of Ni crystals containing 1 at.% Si. The channeling method was used to investigate interactions between the radiation-induced defects and the silicon atoms. From the measured minimum yields and from the shape of the angular scans the fraction of silicon atoms is determined, which are displaced into the <100> and <110> channels due to proton or helium irradiations and subsequent annealing treatments. In undamaged crystals about 98 % of the silicon atoms are on normal lattice sites. After irradiation a dose dependent fraction of the silicon atoms is displaced 0.05 nm away from the substitutional position indicating the formation of a mixed dumbbell consisting of one selfinterstitial atom and one silicon atom. However, the experimental data can also be interpreted by the assumption of a NiSi₂ complex, in which the silicon atoms are displaced 0.08 nm from the lattice site. Subsequent annealing from 50 K to 160 K does not change the configuration and the concentration of the silicon complexes. At room temperature the silicon atoms in the complex are positioned 0.04 nm from the lattice position. The silicon complexes were totally am ihilated at 400 K.